It is the intention of this conference to stimulate research into the areas of greatest need in relation to breastfeeding and health outcomes which are applicable to both developed and emerging countries. The specific objectives of the proposed meeting are to: 1) re-evaluate protein and energy requirements of the lactating mother and the growing infant (both term and premature) based on new data of dietary intakes and performance outcomes; 2) explore the interrelationships between breastfeeding and infections both from the perspective of milk transmitted infections and the protective effects of human milk against infections; 3) critically appraise new research methodologies which are important for future research design in studies of infant nutrition and health; 4) explore health issues such as environmental contaminants and cultural beliefs which must be considered in the evaluation of health outcomes of breastfed infants around the world; and 5) provide an opportunity for young scientists to present their research in the field of human lactation of funding competitive "Young Investigators" travel awards and special poster sessions at the meeting. With the dynamic state of science, research methodologies must constantly be improved in order to provide more definitive and precise answers to our research questions. Workshop V has been designed to explore in detail one new technological research tool - stable isotopes of doubly labelled water for the assessment of milk production; body composition; and energy expenditure - and one biostatistical tool - that of the well designed prospective epidemiological (Multi-centered) survey. Forty-one outstanding scientists from the USA, Canada, Central and South America, Europe, Pakistan, India and Japan will be invited. The converence will be held in San Jose, Costa Rica, November 2-6, 1988. The theme of this International Conference, "Breastfeeding Nutrition, Infections and Infant Growth is Developed and Emerging Societies" will be explored through a series of six workshops on specific topics with speakers and discussants and four plenary sessions which are intended to provide summaries of the new information in the field. The information presented at this meeting should impact on public health issues and essential research directions for the immediate future.